58 Johnson super seahorse 35 cooling trouble

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Porto

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Hello, I have a 1958 35 HP Johnson super seahorse with cooling problems. The motor sprays water out of the hole on the back at idle speed and it sprays water out of the hole at low speed, but it stops spraying water at high speed. Not even steam. I was told to remove the thermostat but it had already been removed when I checked for it. I started the motor with the the cover off where the thermostat would go and it sprayed out alot of water, telling me the pump is working. I was told perhaps the motor shaft was too short for the boat but it's a long shaft motor and the plate above the prop is 4 inches below the bottom of the boat and several inches if not a foot below the waterline. I ran the motor at high speed for a few minutes and when I cut it down I could touch the cylinders without getting burnt. They were hot but not "smoking hot". Does this sound like a partial block in the water jacket or something else?
 
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MonDoo

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Re: 58 Johnson super seahorse 35 cooling trouble

No it sound like you need to put a thermostat back in to slow the water down so that it can cool the motor
 
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Porto

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Re: 58 Johnson super seahorse 35 cooling trouble

Thank you, I will try a thermostat, where is one available?<br />Also, with or without a thermostat, shouldn't water spray out of the hole at high speed? I have a 1960 Johnson 18 horse and it sprays a good stream of water from the hole at all speeds.
 
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nimmor

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Re: 58 Johnson super seahorse 35 cooling trouble

You will need not only the thermostat but the thermostat kit. I just got done trying to figure this out over the last month on my 1959 35H.P. Johnson, which shouldn't be much differant from yours. This may turm out to be along post but I will explain everything so you will understand. I got so fed up with not getting water circulating that I tore the whole thing down until I had been everywhere the water went and that was when I understood how this all worked. There are two water discharges in the thermostat housing after the thermostat opens. The one directly below the thermostat goes back to the water pump and the one to the side goes out the pee hole. The complete thermostat kit has a plunger with a spring that goes underneath the thermostat. It requires pressure to build up to push water through causing water to go to the pee hole first. With out this I was not able to get water out the pee hole but like you could take the thermostat housing off and had water. After replacing with the entire kit everything was doing what it was supposed to do. As for where to get the kit look right here in the IBOATS parts section. That is where I got mine. I hope this helps you out.
 
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Porto

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Re: 58 Johnson super seahorse 35 cooling trouble

Thank you for the advice. I looked for the thermostat kit on Iboats.com and they only had them back to a 1959. I wonder if my 1958 takes the same one? <br />My motor has a little white ball that is spring loaded from underneath, below where the thermostat should go. Is this what you're refering to by "a plunger with a spring that goes underneath the thermostat"? If so, was yours missing or not functioning properly before you replaced it? I'm not a mechanic and I don't want to mess up the motor by replacing something I may not do right. Thanks again.
 
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rwise

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Re: 58 Johnson super seahorse 35 cooling trouble

Porto<br />post ytour model number and lets make sure it's a 58. My 58 does not have a place for a theramstat!
 
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Porto

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Re: 58 Johnson super seahorse 35 cooling trouble

The model # is: RDS 20<br />The serial # is: 1841657
 
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alcan

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Re: 58 Johnson super seahorse 35 cooling trouble

The RDS20 is indeed a 1958 35hp model. The high end models for 1958 were fitted with T-stats. The Evinrudes were called Larks and I believe the Johnsons were Javilins. The standard big twin models did not have this feature. Your 1958 model does in fact use the same T-stat as the 59 model. The original OMC part#377148 supercedes to part# 393659 T-stat. Quite often dealers will draw a line as to how far back there parts catologs will go.
 
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Porto

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Re: 58 Johnson super seahorse 35 cooling trouble

Thank you, I will order that thermostat kit now.....
 
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nimmor

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Re: 58 Johnson super seahorse 35 cooling trouble

Yed that is what I was refering to. You asked if mine had a thermastat , the answer was no. I got this old motor on a pretty good deal. It had been sitting around for a few years so I had to do some work but both cylinders are dead on even compression and it seems to run good, what little I have got to take it out. It has been a learning process but fun. So far I have been surprised at how cheap the parts for these old Johnson's are.
 
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Porto

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Re: 58 Johnson super seahorse 35 cooling trouble

I installed the new thermostat kit and still have no water from the "pee hole" at high speed. I get some water and alot of steam at low speed and some water and alot of steam at medium speed but no water or steam at high speed. The steam is new at low and medium speed. I put my fingers over the "pee hole" at high speed and it felt like it was sucking air, not blowing. What does it all mean?
 
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Porto

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Re: 58 Johnson super seahorse 35 cooling trouble

Yes, the impeller is new. I ran the motor with the thermostat cover off and I got a good spray of water there, so I figured the pump was fine but now I'm wondering about the pump housing. What do you guys think?
 
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Porto

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Re: 58 Johnson super seahorse 35 cooling trouble

Any ideas guy's?
 
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Solittle

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Re: 58 Johnson super seahorse 35 cooling trouble

I would put in a complete new water pump. Seeing spray here and there is not really a good indicator of the water (& pressure) going through the coolong system.
 
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K Hultgre

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Re: 58 Johnson super seahorse 35 cooling trouble

Have you checked the temp of the power head with thermal melt sticks.<br />If I remember correctly that vintage motor would spit/spray water out of the upper discharge at slow speeds but during med to full throttle the water would be flowing so fast it just bypasses the upper hole and exits out the passage just above the propeller blades. When I was a-lot younger I remember seeing mostly exhaust coming out the upper hole during WOT on our 57' 35HP.<br /><br />also, if it has been run in saltwater you might have to pull the head and clean the water passages (choked with salt residue) we ran ours for many years around the Delaware Bay, and I distinctly remember the head would come off at least once a year to clean the passages.
 
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Porto

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Re: 58 Johnson super seahorse 35 cooling trouble

Where do I find thermal melt sticks? Thanks....
 
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Porto

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Re: 58 Johnson super seahorse 35 cooling trouble

Does anybody know where I can find these thermal melt sticks? Am I worrying over nothing here?
 
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rwise

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Re: 58 Johnson super seahorse 35 cooling trouble

Can you lay your hand on it with great discomfert(sp)? If its to hot to hold your hand on then its over heating. I have never watched the pee hole on mine so I can't tell you what it does when! Oh, don't burn your self tring this, be carefull!!!
 
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Porto

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Re: 58 Johnson super seahorse 35 cooling trouble

I've tried (seemingly) everywhere and I can't locate thermal melt sticks. Does anyone know where these might be available? Thanks.....
 
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